1. Field of the Invention
The present invention relates generally to printers. More particularly, the present invention relates to ink jet printers having a fire pulse circuit that limits the width of any fire pulses that are deemed to be potentially damaging for a designed heater.
2. Description of the Related Art
Inkjet print heads require well-controlled timing of firing pulses entering a print head having an inkjet heater to maintain a consistent ink viscosity and jetting performance. CMOS thermal inkjet printers are actuated by data signals entering the print head. The current through an inkjet heater is controlled by a high power field effect transistor (power FET) that is actuated by a print head controller. When the power FET is given the correct input voltage pulse on its gate terminal the inkjet heater is able to nucleate the ink in a heater chamber and emit a drop from the nozzle. It is important that the heater receives the appropriate amount of energy in the form of a fire pulse to heat the heater enough to nucleate the ink without damaging the heater.
If the power FET receives an incorrect and excessive fire pulse duration then a heater receiving an excessive fire pulse may be physically damaged. Once the heater is damaged, the heater will no longer print properly or the heater will lose the ability to print, resulting in a noticeable loss of print quality from the printer.